Gastrocnemius
The gastronemius originates on the distal end of the femur and inserts on the calcaneous. The action of this muscle is to extend the ankle and flex the knee. This muscle is what you would think of ass the calf muscle and since it is thevery back of the shank be careful not to damage the muscle while skinning.
Soleus
The soleus originates from the fibula and the medial border of the tibia and inserts on the tendocalcaneous. The action of this mucle is to control plantar flexation. This muscle lies between the gastronemius and the bone so simply reflect the gastronemius to observe this muscle.
Tibialis Anterior
The tibialis anterior muscle originates from the body of the tibia and inserts on the first metatarsal bones in the foot. This muscle provides dorsiflextion and inversion of the foot. This muscle is the fore front muscle of the shank so use caution when isolating so as not to harm this muscle.
Extensor Digitorum Longus
This muscle originates from the anterior lateral condyle of tibia and inserts on the distal surface of the lateral four digits. The action of this muscle is the extension of the toes and ankle. To find this muscle simply remove the skin and connective tissue from around it.
Peroneus Tertuis
The peroneus tertuis originates from distal anterior surface of the fibula and inserts along the distal surface of metatarsal five. The action of this muscle is dorsiflextion and eversion of the foot.
Peroneus Longus
The origin of the peroneus longus is the fibula and its insertion is on the first metatarsal. The action of this muscle is plantar flexation and eversion. This muscle lies adjacent to the peroneus tertuis in the middle of the shank and is fairly simple to isolate.